Piston packing



G. CHRlSTENSO/N PIsToN PACKING Filed July 21, 1957 WW y Nov. 12, 1940.

- cylinder at all times, and under all conditions of Patented Nov. 12, 1940 UNrrED `sfrrnas PATENT OFFICE- azzosa rIs'roN momo George Christensen, Plainield, N. J., assignor to Johns-Manville Corporation, New York, N. Y., a corporation of New York Application July 21, 1937, serial No. 154,365'

6 Claims.

operation to which a piston and cylinder assembly is subjected.

A further object of this invention is to provide a packing for a piston and cylinder assembly which can be initially installed and replaced by removing a minimum of parts from the assembly.

Other objects and advantages, if notspecifi'- cally pointed out, will be apparent to those skilled inthe art from the following detailed description of what is .now considered to be the preferred o embodiment of the invention.

In the drawing: Fig. 1 is a fragmentary, vertical, central sec- I tional View of a piston and cylinder assembly embodying the present invention, and

Fig. 2 is a fragmentary perspective view of the packing cup of the present invention. 4 This invention is capable of being applied to many different types of machines or apparatuses which involve a piston and cylinder assembly, and is not limited to any specific application. It has been found, however, that this invention is particularly applicable to air brake assemblies,

' and power reverse gear assemblies for steam locomotives. For the purpose lof explanation, it has been illustrated' and described as applied to a single acting piston of the type commonly employed in air brake assemblies, but it is to be understood that it is equally applicable to a double acting piston, such as that usually employed in a power reverse gear assembly.,

Referring to Fig. 1; a cylinder 2 is shown which has a cylinder head 4 connected thereto in any suitable manner.

A piston y6 is reciprocable within thecylinder 2 and has a face 8 provided with a groove I0 which is substantially annular in shape, and is wider in cross section within the cylinder head 6 than at the face 8 for a reason which will be later described.

-1in annular ange I2 projects from face 8 towards the cylinder head I.

A packing I 4 is disposed on the piston face 8 between the cylinder wall and the flange I2. The packing I4 (see Fig. 2) comprises a base I t to which an upturned portion I8 is connected.

the piston The upturned portion will usually take the form of a lip or iiange and is provided with an inwardly projecting shoulder 20, and the base I 6 has a bead 22 formed thereon.

The base I6 vand the upturned portion oir liange I8 may begformed of laminated fabric suitably impregnated or frictioned with a material, such as a rubber composition. The bead 22 lis yieldable and may be formedof the same composition as the impregnating material but preferably without reinforcing fabric. The bead 22 may, if desired, be formed from a different material than the Aremainder of the packing, but in its preferred construction it isv formed as previously described. The base I 6 is extended up- 15 wardly along its inner margin as shown at 2l. 'I'he bead 22 has a bulbous cross-sectional shape and is generally shaped to fit within the groove I0 in the piston head 6. The bead 22 may be formed with other cross-sectional shapes if desired, the only requirement being that it iiare or become wider at a point spaced from the base I6 than at its point of connection with the base I6. The .upturned portion 24 of the base I6, the inner edge of the base I6, and the inner wall of the bead 22 form a wall surface 26 of substantial vwidth which assists in securing the packing in position during operation.

The packing Il is applied to the piston 6 by lremoving the cylinder head1, except in original installations `when the packing will be applied before the head I isconnected to theV cylinder 2, and sliding. it over the flange I2 and forcing the bead 22 down into the groove I0 tofsubstantially ll the groove and thereby lock the packing I4 to the piston head 6, as well as provide an elcient uid seal between the packing and piston head.

An expander ring 28 of a conventional type may be snapped into position around the inside of the packing ange I8, and is prevented from slipping ofi.' of the packing by the shoulder 20.

The packing structure previously described is maintained in iiuid sealing contact with the piston 8 at allv times, and there is no tendency for the packing to oat away from the piston head 8 in the cylinder acting against the piston head 8. 'Ihis packing construction also accomplishes the foregoing without the aid of a follower plate 50 instance, and also reduce the expense of main- .C

when the piston is moved by uid pressure withbodiment of the invention herein disclosed with-- out departing from the spirit of the invention. For example..the groove I0 may be made discontinuous and the bead 22 likewise made discontinuous to correspond to the groove I 0. Also, the bead 22 may be placed at other points along Vthe base I6 than at the position shown, if a particular installation Vshould make such a change desirable.

What I claim is:

1l. In combination with a cylinder, a head therefor, a piston reciprocable Within the cylinder and having a face provided with a continuous groove therein, the groove being Wider within the piston than at the face thereof, an annular projection aiixed to said piston providing a continuous flange extending from the face of said piston toward the cylinder head, and a packing cup comprising a base in contact with the piston face and the flange, a portion in contact with the cylinder wall and extending toward the cylinder head to no greater degree than the ange, said base and said portion comprising impregnated fabric, and a bead seated within and substantially filling said groove to prevent relative movement between the piston and packing cup andto provide a Lfluid seal between the same, said bead being composed of areadily yieldable, deformable composition.

2. A` packing cup for assembly with a reciprocable piston having a forward face, an annular Wall projecting from said face, and an annular groove in said face adjacent said wall, said groove being 'of greatest Width at` a point remote from said face, said packing cup comprising a base, a deformable bead formed of plastic material extending from'the plane of said base at the inner periphery thereof and shaped and arranged for yieldable interlocking engagement with said groove, and a continuous upstanding peripheral lip formed. integrally with said base and adapted for sliding and sealing engagement with a cylinder wall, said base andlip comprising a laminated fabric material carrying a rubber-like impregnant.

3. A packing cup for asseinuiy witn a reciprocable piston having a forward face and anannular groove therein, said packing cup comprisso ing a base, a bead extending from the plane of said base and shaped and arranged for yieldable interlocking engagement with said groove, said bead being composed of a yieldable rubber-like material, and a continuous upstanding peripheral lip formed integrally with said basevand adapted for sliding and sealing engagement with the cylinder wall, said base and lip comprising a laminated fabric material carrying a rubber-like impregnant.

4. In combination a cylinder, a head therefor, a piston reciprocable Within said cylinder and having a forward face with an annular groove therein of greatest width at a point remote from said face, a packing cup carried wholly by said piston for reciprocation therewith, said packing ,cup comprising a base in contact with the piston face and including a bead composed of a readily deformable material and substantially comple# mental in shape to said groove and seated therein, a peripheral projecting lip formed integrally with said base and in sealing engagement with said cylinder wall, said base and lip comprising fabric carrying a rubber-like impregnant, means for maintaining said lip in said sealing engagement, and a member projecting from the face of said piston to an extent suicient to prevent `crushing of said upstanding lip against said cylinder head in any forward movement of said piston.

5. A packing cup for assembly with a reciprocable piston having a forward face and an annular groove therein, said packing cup comprising an annular base and a bead composed of a readily deformable, kplastice composition integral with said base and extending from the -plane thereof and shaped and arranged for yieldable, interlocking engagement with said groove, and an upstanding annular lip carried by said base at'its outer periphery and adapted for sliding and sealing engagement with the cylinder wall, said base and lip comprising an impregnated fabric.

6. In combination a cylinder, a piston reciprocable within said cylinder and having a forward face, an annular wall projecting from said face and an annular groove in said face adjacent said wall and defining a continuation thereof, and a packing cup carried by said piston for reciprocation therewith, said packing cup comprising an annular base in contact with the piston face with its inner periphery pressed against said annular Wall, and a bead composed of a readily deformable, yieldable composition integral with said base and extending from the plane thereof and seated within said groove, the bead and groove being shaped for wedging, interlocking and sealing engagement, and a peripheral upstandng lip formed integrally with said base and in seating engagement with a. wall of the cylinder, said base and lip comprising fabric carrying a rubber-like impregnant.

' GEORGE CHRISTENSON.

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